SlideShare a Scribd company logo

Brk 135 t-ccna_switching

•
P
parthasn83

This document provides an overview and configuration guidance for Cisco's CCNA Switching certification course. It covers topics like high availability campus network design, spanning tree protocol operations and configurations, rapid PVST+, and troubleshooting techniques. The agenda includes discussions of STP variants, operations, port states, timers, and features to optimize convergence like PortFast, UplinkFast, BackboneFast, and root guard.

Technology
1 of 60
Downloaded 189 times
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
© 2008 Cisco Systems, Inc. All rights reserved. Cisco Public BRK-135T CCNA Switching 1 CCNA Switching Snezhy Neshkova, CCIE # 11931 Technical Manager US Academy Conference 2008
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 2 Agenda ƒ High Availability Campus Design Overview ƒ STP Operations ƒ STP Variances ƒ Rapid PVST+ Configuration ƒ Troubleshooting Spanning Tree Protocol
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 3 Spanning Tree Protocol
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 4 High Availability Campus Design ƒ Modularity, structure, and hierarchy ƒ Network redundancy and network protocols Link redundancy (trunks, channels and fiber) Redundancy in the distribution block Redundancy and routing design ƒ Resilient campusnetwork designSiSiSiSi Intranet Internet
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 5 Data Center WAN Internet Si Si Si Si Si Si Si Si Si Si Si Si Si Si Access Core Distribution Distribution Access High Availability Campus Design Structure, Modularity, and Hierarchy
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 6 Hierarchical Campus Network Server Farm WAN Internet PSTN Si Si Si Si Si Si Si Si Si Si Si Si Not This !! Structure, Modularity and Hierarchy
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 7 SiSiSiSiSiSiSiSiSiSiSiSi Hierarchical Network Design Building Block Access Distribution Core Distribution Access• Offers hierarchy—each layer has specific role • Modular topology—building blocks • Easy to grow, understand, and troubleshoot • Creates small fault domains— Clear demarcations and isolation • Promotes load balancing and redundancy • Promotes deterministic traffic patterns • Incorporates balance of both Layer 2 and Layer 3 technology, leveraging the strength of both• Utilizes Layer 3 Routing for load balancing, fast convergence, scalability, and control Without a Rock Solid Foundation the Rest Doesn’t Matter
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 8 Access Layer Feature Rich Environment ƒ It’s not just about connectivity ƒ Layer 2/Layer 3 feature rich environment; convergence, HA, security, QoS, IP multicast, etc. ƒ Intelligent network services: QoS, trust boundary, broadcast suppression, IGMP snooping ƒ Intelligent network services: PVST+, Rapid PVST+, EIGRP, OSPF, DTP, PAgP/LACP, UDLD, FlexLink, etc ƒ Cisco Catalyst integrated security features IBNS (802.1x), (CISF): port security, DHCP snooping, DAI, IPSG, etc. ƒ Automatic phone discovery, conditional trust boundary, power over Ethernet, auxiliary VLAN, etc. ƒ Spanning tree toolkit: Portfast, UplinkFast, BackboneFast, LoopGuard, BPDUGuard, BPDUFilter, RootGuard, etc. Access Distribution CoreSiSiSiSiSiSiSiSi
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 9 SiSiSiSi Distribution Layer Policy, Convergence, QoS, and High Availability ƒ Availability, load balancing, QoS and provisioning are the important considerations at this layer ƒ Aggregates wiring closets (access layer) and uplinks to core ƒ Protects core from high density peering and problems in access layer ƒ Route summarization, fast convergence, redundant pathload sharing ƒ HSRP or GLBP to provide first hop redundancySiSiSiSi Access Distribution Core
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 10 SiSiSiSi Core Layer Scalability, High Availability, and Fast Convergence ƒ Backbone for thenetwork -connects network building blocks ƒ Performance and stability vs. complexity -less is more in the core ƒ Aggregation point for distribution layer ƒ Separate core layer helpsin scalability duringfuture growth ƒ Keep the design technology- independentSiSiSiSi Access Distribution Core
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 11 Foundation Services ƒ Layer 3 routing protocols ƒ Layer 2 redundancy—spanning tree PVST+ - STP (802.1D-1998) Rapid PVST+ - RSTP (802.D-2004) ƒ Trunking protocols—(isl/.1q) ƒ Unidirectional link detection ƒ Load balancing Etherchannel link aggregation CEF equal cost load balancing ƒ First hop redundancy protocols VRRP, HSRP, and GLBP Spanning Tree Routing HSRP GLBP Trunking LoadBalancing
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 12 Best Practices— Spanning Configuration ƒ Onlywhen you have to! ƒ More common in thedata center ƒ Required when a VLAN spans access layer switches ƒ Required to protect against ‘user side’loops ƒ Use Rapid PVST+ for best convergence ƒ Take advantage of the Spanning Tree Toolkit Data Center WAN Internet Layer 3 Equal Cost Links Layer 3 Equal Cost Links Layer2 Loops Same VLAN Same VLAN Same VLAN Si Si Si Si Si Si Si Si Si Si Si Si Si Si
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 13 Multilayer Network Design ƒ Each access switch hasunique VLANs ƒ No layer 2 loops ƒ Layer 3 link between distribution ƒ No blocked links ƒ At least some VLANs span multiple access switches ƒ Layer 2 loops ƒ Layer 2 and 3 running over link between distribution ƒ Blocked linksSiSiSiSiSiSiSiSi Vlan 10 Vlan 20 Vlan 30 Vlan 30 Vlan 30 Vlan 30 Layer 2 Access with Layer 3 Distribution
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 14 Routing to the Edge Layer 3 Distribution with Layer 3 Access ƒ Move the Layer 2/3 demarcation to the network edge ƒ Upstream convergence times triggered by hardware detection of light lost from upstream neighbor ƒ Beneficial for the right environment 10.1.20.0 10.1.120.0 VLAN 20 Data VLAN 120 Voice VLAN 40 Data VLAN 140 Voice 10.1.40.0 10.1.140.0 EIGRP/OSPF EIGRP/OSPF GLBP ModelSiSiSiSi Layer 3 Layer 2 Layer 3 Layer 2 EIGRP/OSPF EIGRP/OSPF
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 15 STP Operations STP Convergence Steps Step 1: Elect a Root Bridge The switch with the lowest Bridge ID wins; the standard Bridge ID is 2-byte priority followed by a MAC address unique for the switch Step 2: Elect the Root Ports The one port on the each switch with the least cost path back to the root Step 3: Elect the Designated and Non-Designated Ports When multiple switches connect to the same segment; this is the switch that forwards the least cost Hello onto the segment Three step process STP uses to create a loop-free topology
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 16 STP Operations STP Port States and BPDU Timers in the Operation of STP Port States Processes Blocking Listening Learning Forwarding Disable Receives and process BPDUs 9 9 9 9 8 Forward data frames received on interface 8 8 8 9 8 Forward data frames switched from another interface 8 8 8 9 8 Learn MAC address 8 8 9 9 8 1Return to blocking if not lowest cost path to root bridge BPDU Timers Hello Time ƒ The hello time is the time between each BPDU frame that is sent on a port ƒ This is equal to 2 seconds by default, but can be tuned to be between 1 and 10 seconds Forward Delay ƒ The forward delay is the time spent in the listening and learning state ƒ This is by default equal to 15 seconds for each state, but can be tuned to be between 4 and 30 seconds Maximum Age ƒ The max age timer controls the maximum length of time a switch port saves configuration BPDU information ƒ This is 20 seconds by default, but can be tuned to be between 6 and 40 seconds
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 17 A Root C Peer D Peer 1 2 2 1 2 2 1 RP DP DP RP DP DP RP NDP 1 Core Distribution B Peer 32768:000000000002 8192:000000000001 32768:000000000004 32768:000000000003 Root Ports: Port with Least Cost Path to the Root Bridge Nondesignated Ports: Ports in Blocking Designated Ports: Ports Selected for Forwarding Direction of BPDU Flow Layer 2 Spanning Tree
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 18 Layer 2 Hardening ƒ Place the Root where you want it Root Primary/Secondary Macro HSRP/GLBP ƒ The root bridge should stay where you put it Rootguard Loopguard UplinkFast UDLD ƒ Only end station traffic should be seen on an edge port BPDU Guard Root Guard PortFast Port-securitySiSiSiSi BPDU Guard or Rootguard PortFast Rootguard UplinkFast STP Root Spanning Tree Should Behave the Way You Expect Loopguard Loopguard Port-Security
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 19 *Also Supported with MST and Rapid PVST+ Spanning Tree Features ƒ PortFast*:Bypass listening-learning phase for access port ƒ UplinkFast:Three to five seconds convergence after link failure ƒ BackboneFast:Cuts convergence time by Max_Age for indirect failure ƒ LoopGuard*:Prevents alternate or root port from becoming designated in absence of BPDUs ƒ RootGuard*:Prevents external switches from becoming root ƒ BPDUGuard*:Disable PortFast enabled port if a BPDU is received ƒ BPDUFilter*:Do not send or receive BPDUs on PortFast-enabled ports Wiring Closet Switch Distribution Switches Root F F F F F X BSiSiSiSi
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 20 What Is Root Guard? SiSiSiSiSiSiSiSi Root GLBP Active RP DP BP ƒ Root guard forces a Layer2 LAN interface to be a designated port ƒ If spanning-tree calculations cause a port to be selected as the root port, the port transitions to the root- inconsistent(blocked) state to prevent the customer's switch from becoming the root switch or being in the path to the root. SW(config)# interface fa0/3 SWconfig-if)# spanning-tree rootguard
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 21 UplinkFast ƒ Spanning Tree enhancement to reduce failover convergence time ƒ Used when recovery path is known and predictable ƒ Enabled on access switch ƒ Bypasses ‘listening’and ‘learning’stages of STP ƒ Reduces failover time to 2–3 seconds from 30 seconds ƒ Auto-populates upstream address tables (dummy mcast) 2 F F F B 1 Root F F 1SiSiSiSi Switch(config)# spanning-tree uplinkfast
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 22 BackboneFast ƒ Spanning Tree enhancement to reduce failover convergence time ƒ Targeted at indirectfailures ƒ Enabled on all switches ƒ Bypasses ‘max-age’ ƒ Reduces failover time to 30 seconds from 50 seconds 3 F F F F SiSiSiSi F B Root Switch(config)# spanning-tree backbonefast
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 23 PortFastSiSiSiSiSiSiSiSi Root RP DP ƒUsed on Access Ports (Edge Port) that are NOT connected to other switches or hubs ƒOptimizes the convergence by simply ignoring the Listening and Learning states of the port ƒImmediately puts the port into Forwarding state when the port is physically working BP Switch(config-if)# spanning-tree portfast
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 24 What Is BPDU Guard? SiSiSiSiSiSiSiSi Root ƒ PortFast BPDU guard can prevent loops by moving PortFast-configured interfaces that receive BPDUs to errdisable,rather than running Spanning Tree across that port ƒ This keeps ports configured with PortFast from being incorrectly connected to another switch Switch(config)# spanning-tree portfast bpduguard or Switch(config-if)# spanning-tree bpduguard enable 1w2d: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port FastEthernet3/1 with BPDU Guard enabled. Disabling port. 1w2d: %PM-4-ERR_DISABLE: bpduguard error detected on Fa3/1, putting Fa3/1 in err-disable state
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 25 Link Redundancy—UDLD Aggressive Mode UDLD ƒ Default UDLD timers (15 second hellos) are intended to take down link prior to 802.1d spanning tree listening/learning transition ƒ Aggressive mode—after aging on a previously bi-directional link—tries eight times (once per second) to reestablish connection then err- disables port ƒ Aggressive mode protects against One side of a link has a port stuck (both Tx and Rx) One side of a link remains up while the other side of the link has gone down ! Global configuration udld aggressive udld message time 7 ! Interface interface GigabitEthernet8/1 udld port aggressiveSiSiSiSi Tx Tx Rx Rx
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 26 Spanning Tree Verification 3550# show spanning-tree summary Switch is in pvst mode Root bridge for: VLAN0001 EtherChannel misconfig guard is enabled Extended system ID is enabled Portfast is disabled by default PortFast BPDU Guard is disabled by default Portfast BPDU Filter is disabled by default Loopguard is disabled by default UplinkFast is disabled BackboneFast is disabled Pathcost method used is short Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 0 0 0 2 2 VLAN0005 0 0 0 2 2 ---------------------- -------- --------- -------- ---------- ---------- 2 vlans 0 0 0 4 4 3550# show spanning-tree VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 24577 Address 0005.ddc5.8300 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 24577 (priority 24576 sys-id-ext 1) Address 0005.ddc5.8300 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 15 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- ------------------------ Gi0/12 Desg FWD 19 128.12 P2p Po1 Desg FWD 3 128.65 P2p (etc, for additional vlans)
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 27 Spanning Tree Best Practice “How Can I Have a Spanning Tree Loop? I Don’t Have Spanning Tree Enabled?” Cisco Recommends Leaving STP-Enabled for the Following Reasons: ƒ If there is a loop (induced by mispatching, bad cable, and so on), STP will prevent detrimental effects to the network caused by multicast and broadcast data ƒ Protection against an EtherChannelbreaking down ƒ Most networks are configured with STP, giving it maximum field exposure; more exposure generally equates to stable code ƒ Protection against dual attached NICs misbehaving (or bridging enabled on servers) ƒ The software for many protocols (such as PAgP, IGMP snooping, and trunking) is closely related to STP; running without STP may lead to undesirable results
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 28 Spanning Tree Standards and Features Spanning Tree Toolkit, 802.1D, 802.1s, 802.1w ƒ 802.1D/1998:Legacy standard for bridging and Spanning Tree (STP) ƒ 802.1D/2004:Updated bridging and STP standard; includes 802.1s, 802.1t, and 802.1w ƒ 802.1s:Multiple Spanning Tree Protocol (MSTP)—maps multiple VLANs into the same Spanning Tree instance ƒ 802.1t:MAC address reduction/extended system ID—moves some BPDU bits to high-numbered VLANs from the priority field, which constrains the possible values for bridge priority; unique “MAC”per chassis not port ƒ 802.1w:Rapid Spanning Tree Protocol (RSTP)—improved convergence over 1998 STP by adding roles to ports and enhancing BPDU exchanges ƒ Cisco Features:Per VLAN Spanning Tree (PVST), PVST+, UpLinkFast, BackboneFast, BPDU Guard, RootGuard, LoopGuard, UDLD A B STOP
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 29 STP Variance DEC STP pre-IEEE 802.1t—802.1d maintenance IEEE 802.1w—Rapid STP (RSTP) 802.1D—Classic STP 802.1s—Multiple STP (MST)
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 30 Cisco Spanning-Tree toolkit PortFast Lets the access port bypass the listening and learning phases Root Guard Prevents external switches from becoming the root STP enhancements to 802.1(d,s,w) BackboneFast Cuts convergence time by MaxAge for indirect failure UplinkFast Provides 3-to-5 second convergence after link failure Loop Guard Prevents the alternate or root port from being elected unless Bridge Protocol Data Units (BPDUs) are present BPDU Guard Disables a PortFast-enabled port if a BPDU is received BPDU Filter Prevents sending/receiving BPDUs on PortFast-enabled ports
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 31 STP Variance Per-VLAN Spanning Tree Plus (PVST+) Provides a separate 802.1D spanning tree instance for each VLAN configured in the network. This includes PortFast, UplinkFast, BackboneFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard. MST Provides up to 16 instances of RSTP (802.1w) and combines many VLANS with the same physical and logical topology into a common RSTP instance. This includes, PortFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard. Cisco Proprietary Rapid PVST+ Provides an instance of RSTP (802.1w) per VLAN. This includes PortFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard.
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 32 05101520253035PVST+Rapid PVST+ UpstreamDownstream Optimizing L2 Convergence ƒ Rapid-PVST+ greatly improves the restoration times for any VLAN that requires a topology convergence due to link UP ƒ Rapid-PVST+ also greatly improves convergence time over Backbone fast for any indirect link failures ƒ PVST+ (802.1d) Traditional Spanning Tree Implementation ƒ Rapid PVST+ (802.1w) Scales to large size (~10,000 logical ports) Easy to implement, proven, scales ƒ MST (802.1s) Permits very large scale STP implementations (~30,000 logical ports) Not as flexible as Rapid PVST+ Time to Restore Data Flows (sec) PVST+, Rapid PVST+ or MST
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 33 RAPID SPANNING TREE 802.1w
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 34 RSTP: New Concepts ƒ New Port Roles and States ƒ Modified BPDU ƒ Proposal/Agreement messages between bridges ƒ BPDU handling ƒ New topology change mechanism ƒ PVST+/802.1D Compatibility
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 35 Rapid PVST+ ƒ Rapid PVST+ is the IEEE 802.1w (RSTP) standard implemented per VLAN. ƒ Each Rapid PVST+ instance on a VLAN has a single root switch. You can enable and disable STP on a per- VLAN basis when you are running Rapid PVST+. ƒ Rapid PVST+ uses point-to-point wiring to provide rapid convergence of the spanning tree. ƒ The spanning tree reconfiguration can occur in less than 1 second with Rapid PVST+ (in contrast to 50 seconds with the default settings in the 802.1D STP).
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 36 Rapid PVST+ defines 4 port roles: ƒ Root port -If Rapid PVST+ selects a new root port, it blocks the old root port and immediately transitions the new root port to the forwarding state. ƒ Designated port ƒ Alternate port ƒ Backup port Port state (blocking, forwarding, learning) is independent from the role Rapid PVST+ roles (1) Both blocking
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 37 Rapid PVST+ roles (2) Root A B R R Root Port R Root Port: Port receiving the best BPDU for the bridge – shortest path to the Root in terms of path cost
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 38 Rapid PVST+ roles (3) Root A B R D D D R Root Port R Designated Port D Designated Port: Port sending the best BPDU on a segment
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 39 Rapid PVST+ roles (4) Root A B R D D D R Root Port R Designated Port D Alternate Port Alternate Port: Port blocked by BPDUs from a different bridge – redundant path to the Root
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 40 Rapid PVST+ roles (5) Root A B R D D D R Root Port R Designated Port D Backup Port Alternate Port Backup Port: Port blocked by BPDUs sent from the same bridge – redundant path to a segment
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 41 Modified BPDU ƒ Protocol version now 2 (was 0) ƒ No more distinct TCN BPDU ƒ Flag field changes • 802.1D bridges drop RSTP BPDUs
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 42 Modified BPDU (2) ƒ BPDUs now act as keepalives: – All bridges send BPDUs every hello time (PVST+ used to relay BPDUs from the root) – Port information invalidated in 3 x hello time max Ù3 BPDUs lost – No more Max Age or Message Age fields – a hop count is used instead inside a region ÖFaster failure detection
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 43 Agreement/Proposal ƒ Explicit handshake mechanism between bridges ƒ Upon link up event, bridge sends a proposal to become designated for that segment (designated bridge is the one leading to the root) ƒ Response is an agreementif remote bridge selects the port on which it received the proposal as its root port ƒ As soon as agreement is received, port moves to forwarding
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 44 Agreement/Proposal A B C B Root ƒ Ahas a better priority than B ƒ Asends a proposal to Bto become designated ƒ Bcompares the received priority and replies with an agreement –B’s port becomes Root Port • The same process is repeated when a new bridge is inserted Prop Agree
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 45 Rapid Transition ƒFor a rapid transition to occur • Make sure you properly identify: » Edge ports (enabled via Portfast) » Point-to-point links (derived from duplex mode by default) ƒIt is very important to check duplex settings between two bridges –else, no Proposal/Agreement mechanism !
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 46 Protocol Migration (1) Mix of 802.1D and 802.1w Bridges: ƒ 1D bridges drop 1w BPDUs Ö1D Bridges always end up sending BPDUs • After Migration Delay (3s), RSTP bridge starts sending 802.1D BPDU if it detects a legacy bridge (on a per-port basis). A (1w) B (1w) C (1D) RSTP BPDU STP BPDU
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 47 Protocol Migration(2) • Cannot detect if 802.1D bridge is removed if it is not designated (otherwise it would send BPDUs). • If C goes away, force protocol migration manually (set spantree mst x/y redetect- neighbor) • 1D-1w interoperability = slow convergence: Ötry to avoid it. A (1w) B (1w) C (1D) STP BPDU
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 48 Configuring Rapid-PVST+ ƒ RSTP fast convergence on a per-VLAN basis ƒ Each VLAN runs its own RSTP instance and sends its own RSTP BPDU, just like PVST+ CiscoIOS# configure terminal CiscoIOS(config)# spanning-tree mode rapid-pvst+
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 49 Configuring Rapid-PVST+ in Distribution Dist-2 Dist-1 FWD: VLANs 6-10 BLK: VLANs 1-5 Trunk FWD: VLANs 1-5 BLK: VLANs 6-10 FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 1-5 Sec. Root: VLANs 6-10 Root: VLANs 6-10 Sec. Root: VLANs 1-5 FWD: VLANs 6-10 BLK: VLANs 1-5 Cisco IOS spanning-tree extend system-id spanning-tree mode rapid-pvst+ ! Set spanning tree mode to rapid-pvst+ spanning-tree vlan 1-5 root primary spanning-tree vlan 6-10 root secondary
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 50 Configuring Rapid-PVST+ in Access Trunk FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 1-5 Sec. Root: VLANs 6-10 FWD: VLANs 6-10 BLK: VLANs 1-5 FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 6-10 Sec. Root: VLANs 1-5 FWD: VLANs 6-10 BLK: VLANs 1-5 Acc-1 Acc-1 CiscoIOS spanning-tree extend system-id ! Enable MAC address reduction. This is not a requirement spanning-tree mode rapid-pvst+ ! Set spanning tree mode to rapid-pvst+
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 51 Spanning Tree Protocol Troubleshooting Methodology ƒ Start now—be proactive ƒ Divide and conquer ƒ Document Spanning Tree topology ƒ Implement Spanning Tree enhancement features ƒ Develop recovery plan to include data collection for root cause analysis Data Center WAN Internet Layer 3 Equal Cost Links Layer 3 Equal Cost Links Layer2 Loops Si Si Si Si Si Si Si Si Si Si Si Si Si Si
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 52 Spanning Tree Protocol Documenting Spanning Tree Topology Corporate Network 3/1–4 3/1–4 1/1 1/1 Gig 0/1 155.3.77.254 Gig 0/1 155.3.76.254 VLAN186 VLAN187 Root: 1,3,5,7,9,187 0001.c912.7800 Root: 2,4,6,8,186 0003.6b73.9700 F: 1,2,3,4,5,6,7,8,9 B: 4 F: 1,2,3,4,5,6,7,8,9 4/1 4/1 4/2 4/2 4/3 4/3 4/4 4/4 1/1 1/2 1/1 1/2 1/1 1/2 1/1 1/2 0001.c967.7800 DIST-01 192.168.1.1 DIST-02 192.168.1.2 Closet1 192.168.1.11 Closet2 192.168.1.12 Closet3 192.168.1.13 Closet4 192.168.1.14 0001.c9dd.7800 0001.c932.9700 0001.c949.9700 F: 1,2,3 F: 1,4,5 F: 1,6,7 F: 1,8,9 B: 1,3 B: 2 F: 1,2,3 F: 1,4,5 F: 1,6,7 F: 1,8,9 B: 1,5 B: 1,7 B: 6 B: 1,9 B: 8
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 53 Spanning Tree Protocol STP Loop Recovery ƒ Do not power off switches—pull/shut redundant links ƒ If possible, initially disable ports that should be blocking ƒ Check and physically remove the connections to the ports that should be blocking ƒ Set up remote access to your network and call the TAC
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 54 IOS#show spanning-tree vlan 1 brief VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 1 Address 0060.8355.7b00 Cost 23 Port 1 (GigabitEthernet1/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 0007.0e8f.0880 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Interface Designated Name Port ID Prio Cost Sts Cost Bridge ID Port ID -------------------------- ----------- ------ ------- ------- GigabitEthernet1/1 128.1 128 4 FWD 67 32768 0005.5f33.dc01 128.1 FastEthernet3/48 128.176 128 19 FWD 48 32768 0030.7bdd.5080 128.16 Spanning Tree Protocol Troubleshooting Commands
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 55 IOS#show spanning-tree vlan 1 VLAN0001 Spanning tree enabled protocol rstp Root ID Priority 32768 Address 0030.7b4e.4801 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32768 Address 0030.7b4e.4801 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- ------------------------ Fa2/1 Desg FWD 19 128.129 P2p Peer(STP) Spanning Tree Protocol Troubleshooting Commands
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 56 IOS#show spanning-tree summary Root bridge for: VLAN0010. Extended system ID is enabled PortFast BPDU Guard is enabled EtherChannel misconfiguration guard is disabled UplinkFast is disabled BackboneFast is enabled Default pathcost method used is short Name Blocking Listening Learning Forwarding STP Active ------------------------------------- ------------- ------------- ---------------- -------- VLAN0001 0 0 0 2 2 VLAN0010 0 0 0 1 1 VLAN1002 0 0 0 1 1 VLAN1003 0 0 0 1 1 VLAN1004 0 0 0 1 1 VLAN1005 0 0 0 1 1 ------------------------ ------------- ------------- ------------- ---------------- 6 VLANs 0 00 7 7 Spanning Tree Protocol Troubleshooting Commands Root for Listed VLANs
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 57 IOS# show proc cpu CPU utilization for five seconds: 1%/0%; one minute: 2%; five minutes: 2% PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process 1 0 1 0 0.00% 0.00% 0.00% 0 Chunk Manager <…some output removed…> 79 0 256 0 0.00% 0.00% 0.00% 0 mls-msc Process 80 30508 461976 66 0.40% 0.43% 0.44% 0 Spanning Tree 81 108 27024 3 0.00% 0.00% 0.00% 0 Ethchnl <…some output removed…> 162 12 41 292 0.00% 0.01% 0.00% 1 Virtual Exec IOS# show spanning-tree summary <…some output removed…> Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 1 0 0 1 2 <…some output removed…> VLAN1005 0 0 0 1 1 ---------------------- -------- --------- -------- ---------- ---------- 282 vlans 1 0 0 282 283 Spanning Tree Protocol Troubleshooting Commands Number of Spanning Tree Instances
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 58 IOS#show spanning-tree vlan 1 detail VLAN0001 is executing the ieee compatible Spanning Tree protocol Bridge Identifier has priority 32768, address 0005.7495.9101 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32768, address 0001.c912.7800 Root port is 70 (GigabitEthernet2/6), cost of root path is 4 Topology change flag not set, detected flag not set Number of topology changes 4 last change occurred 02:17:20 ago from Port-channel1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 70 (GigabitEthernet2/6) of VLAN0001 is forwarding Port path cost 4, Port priority 128, Port Identifier 128.70. Designated root has priority 32768, address 0001.c912.7800 Designated bridge has priority 32768, address 0001.c912.7800 Designated port id is 128.70, designated path cost 0 Timers: message age 2, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default BPDU: sent 7, received 4162 Port 833 (Port-channel1) of VLAN0001 is blocking Port path cost 4, Port priority 128, Port Identifier 128.833. Designated root has priority 32768, address 0001.c912.7800 Designated bridge has priority 32768, address 0001.c912.7800 Designated port id is 128.769, designated path cost 0 Timers: message age 1, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default BPDU: sent 4, received 134836 Spanning Tree Protocol Troubleshooting Topology Change Don’t Forget PortFast
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 59
BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 60

More Related Content

PPTX
CCNA v6.0 ITN - Chapter 02
Irsandi Hasan
 
PDF
CCNAv5 - S2: Chapter2 Basic Switching Concepts and Configuration
Vuz Dở Hơi
 
PDF
Difference b/w STP RSTP PVST & MSTP
Netwax Lab
 
PPTX
CCNA v6.0 ITN - Chapter 04
Irsandi Hasan
 
PPT
CCNA SUMMER TRAINNING PPT
Nishant Goel
 
PDF
STP (spanning tree protocol)
Netwax Lab
 
PPTX
CCNA v6.0 ITN - Chapter 06
Irsandi Hasan
 
PPTX
ccna project on topic company infrastructure
Prince Gautam
 
CCNA v6.0 ITN - Chapter 02
Irsandi Hasan
 
CCNAv5 - S2: Chapter2 Basic Switching Concepts and Configuration
Vuz Dở Hơi
 
Difference b/w STP RSTP PVST & MSTP
Netwax Lab
 
CCNA v6.0 ITN - Chapter 04
Irsandi Hasan
 
CCNA SUMMER TRAINNING PPT
Nishant Goel
 
STP (spanning tree protocol)
Netwax Lab
 
CCNA v6.0 ITN - Chapter 06
Irsandi Hasan
 
ccna project on topic company infrastructure
Prince Gautam
 

What's hot (20)

PPTX
CCNA 1 Routing and Switching v5.0 Chapter 3
Nil Menon
 
PPTX
CCNA ppt Day 1
VISHNU N
 
PDF
RSTP (rapid spanning tree protocol)
Netwax Lab
 
PDF
Modulo 4 cisco ccna v7 para estudiantes d
SebastianAcevedoGome1
 
PPTX
bgp protocol
Sukanya Sanyal
 
PPTX
CCNA 1 Routing and Switching v5.0 Chapter 9
Nil Menon
 
PPTX
ccna summer training ppt ( Cisco certified network analysis) ppt. by Traun k...
Tarun Khaneja
 
PPTX
Ccna PPT
AIRTEL
 
PDF
Overview of Spanning Tree Protocol (STP & RSTP)
Peter R. Egli
 
PDF
MPLS Presentation
Unni Kannan VijayaKumar
 
PPT
Static Routing
Sachii Dosti
 
PPTX
CCNA 2 Routing and Switching v5.0 Chapter 3
Nil Menon
 
PPTX
CCNA v6.0 ITN - Chapter 05
Irsandi Hasan
 
PDF
Ccna rse chp7 Access Control List (ACL)
newbie2019
 
PDF
CCNAv5 - S2: Chapter 6 Static Routing
Vuz Dở Hơi
 
PPT
Static Routing
Kishore Kumar
 
PPTX
ITN_Module_6.pptx
argost1003
 
PDF
CCNAv5 - S4: Chapter3 Point to-point Connections
Vuz Dở Hơi
 
PDF
CCNAv5 - S2: Chapter1 Introsuction to switched networks
Vuz Dở Hơi
 
PPT
VTP
Alberto Jimenez
 
CCNA 1 Routing and Switching v5.0 Chapter 3
Nil Menon
 
CCNA ppt Day 1
VISHNU N
 
RSTP (rapid spanning tree protocol)
Netwax Lab
 
Modulo 4 cisco ccna v7 para estudiantes d
SebastianAcevedoGome1
 
bgp protocol
Sukanya Sanyal
 
CCNA 1 Routing and Switching v5.0 Chapter 9
Nil Menon
 
ccna summer training ppt ( Cisco certified network analysis) ppt. by Traun k...
Tarun Khaneja
 
Ccna PPT
AIRTEL
 
Overview of Spanning Tree Protocol (STP & RSTP)
Peter R. Egli
 
MPLS Presentation
Unni Kannan VijayaKumar
 
Static Routing
Sachii Dosti
 
CCNA 2 Routing and Switching v5.0 Chapter 3
Nil Menon
 
CCNA v6.0 ITN - Chapter 05
Irsandi Hasan
 
Ccna rse chp7 Access Control List (ACL)
newbie2019
 
CCNAv5 - S2: Chapter 6 Static Routing
Vuz Dở Hơi
 
Static Routing
Kishore Kumar
 
ITN_Module_6.pptx
argost1003
 
CCNAv5 - S4: Chapter3 Point to-point Connections
Vuz Dở Hơi
 
CCNAv5 - S2: Chapter1 Introsuction to switched networks
Vuz Dở Hơi
 
VTP
Alberto Jimenez
 
Ad

Similar to Brk 135 t-ccna_switching (20)

PDF
multilayer-campus-architectures-and-design-principles
Chris S Chen
 
PDF
Advanced enterprise campus design. routed access (2015 milan)
slide_site
 
PPTX
CCNP Switching Chapter 1
Chaing Ravuth
 
PPTX
Cisco Switch details required to troubleshoot PPT.pptx
GurdarshanSingh45
 
PPT
CCNA Advanced Switching
Dsunte Wilson
 
PDF
5 продвинутых технологий Cisco, которые нужно знать
SkillFactory
 
PPT
Icnd210 s02l02
computerlenguyen
 
PPT
CCNA Discovery 3 - Chapter 3
Irsandi Hasan
 
PPT
CCNA Exploration 3 - Chapter 5
Irsandi Hasan
 
PPTX
CCNA3 Verson6 Chapter3
Chaing Ravuth
 
PPTX
ENCOR_Chapter_2_Spanning_Tree presentation
CuongNguyen700595
 
PPTX
CCNP Switching Chapter 5
Chaing Ravuth
 
PDF
CCNAv5 - S3: Chapter2 Lan Redundancy
Vuz Dở Hơi
 
PPTX
CCNA (R & S) Module 04 - Scaling Networks - Chapter 3
Waqas Ahmed Nawaz
 
PPTX
Switching techniques in networking and uses
lochanraj1
 
PDF
Cisco-Press-CCNP-and-CCIE-Enterprise-Core-ENCOR-350-401-Official-Cert-Guide.pdf
LeeRonald2
 
PPT
ACIT - CCNA Training Course Topic - Switch Stp ACIT
Sleek International
 
PDF
Ccnp3 lab 3_3_en
Omar Herrera
 
PPT
01 route routing services
Marcus Reams
 
PPTX
CCNP v6 Route: Implementing IP Routing Chapter1
Andy Juan Sarango Veliz
 
multilayer-campus-architectures-and-design-principles
Chris S Chen
 
Advanced enterprise campus design. routed access (2015 milan)
slide_site
 
CCNP Switching Chapter 1
Chaing Ravuth
 
Cisco Switch details required to troubleshoot PPT.pptx
GurdarshanSingh45
 
CCNA Advanced Switching
Dsunte Wilson
 
5 продвинутых технологий Cisco, которые нужно знать
SkillFactory
 
Icnd210 s02l02
computerlenguyen
 
CCNA Discovery 3 - Chapter 3
Irsandi Hasan
 
CCNA Exploration 3 - Chapter 5
Irsandi Hasan
 
CCNA3 Verson6 Chapter3
Chaing Ravuth
 
ENCOR_Chapter_2_Spanning_Tree presentation
CuongNguyen700595
 
CCNP Switching Chapter 5
Chaing Ravuth
 
CCNAv5 - S3: Chapter2 Lan Redundancy
Vuz Dở Hơi
 
CCNA (R & S) Module 04 - Scaling Networks - Chapter 3
Waqas Ahmed Nawaz
 
Switching techniques in networking and uses
lochanraj1
 
Cisco-Press-CCNP-and-CCIE-Enterprise-Core-ENCOR-350-401-Official-Cert-Guide.pdf
LeeRonald2
 
ACIT - CCNA Training Course Topic - Switch Stp ACIT
Sleek International
 
Ccnp3 lab 3_3_en
Omar Herrera
 
01 route routing services
Marcus Reams
 
CCNP v6 Route: Implementing IP Routing Chapter1
Andy Juan Sarango Veliz
 
Ad

Recently uploaded (20)

PDF
Unlocking the Future- AI Agents Meet Oracle Database 23ai - AIOUG Yatra 2025.pdf
Sandesh Rao
 
PDF
Advances in Ultra High Voltage (UHV) Transmission and Distribution Systems.pdf
Nabajyoti Banik
 
PDF
The Evolution of KM Roles (Presented at Knowledge Summit Dublin 2025)
Enterprise Knowledge
 
PDF
Doc9.....................................
SofiaCollazos
 
PDF
Cloud-Migration-Best-Practices-A-Practical-Guide-to-AWS-Azure-and-Google-Clou...
Artjoker Software Development Company
 
PDF
SparkLabs Primer on Artificial Intelligence 2025
SparkLabs Group
 
PDF
MASTERDECK GRAPHSUMMIT SYDNEY (Public).pdf
Neo4j
 
PPTX
AI and Robotics for Human Well-being.pptx
JAYMIN SUTHAR
 
PDF
Tea4chat - another LLM Project by Kerem Atam
a0m0rajab1
 
PDF
Accelerating Oracle Database 23ai Troubleshooting with Oracle AHF Fleet Insig...
Sandesh Rao
 
PDF
A Strategic Analysis of the MVNO Wave in Emerging Markets.pdf
IPLOOK Networks
 
PDF
Economic Impact of Data Centres to the Malaysian Economy
flintglobalapac
 
PDF
Software Development Methodologies in 2025
KodekX
 
PDF
AI Unleashed - Shaping the Future -Starting Today - AIOUG Yatra 2025 - For Co...
Sandesh Rao
 
PPTX
New ThousandEyes Product Innovations: Cisco Live June 2025
ThousandEyes
 
PDF
REPORT: Heating appliances market in Poland 2024
SPIUG
 
PDF
Google I/O Extended 2025 Baku - all ppts
HusseinMalikMammadli
 
PPTX
cloud computing vai.pptx for the project
vaibhavdobariyal79
 
PPTX
The-Ethical-Hackers-Imperative-Safeguarding-the-Digital-Frontier.pptx
sujalchauhan1305
 
PDF
Get More from Fiori Automation - What’s New, What Works, and What’s Next.pdf
Precisely
 
Unlocking the Future- AI Agents Meet Oracle Database 23ai - AIOUG Yatra 2025.pdf
Sandesh Rao
 
Advances in Ultra High Voltage (UHV) Transmission and Distribution Systems.pdf
Nabajyoti Banik
 
The Evolution of KM Roles (Presented at Knowledge Summit Dublin 2025)
Enterprise Knowledge
 
Doc9.....................................
SofiaCollazos
 
Cloud-Migration-Best-Practices-A-Practical-Guide-to-AWS-Azure-and-Google-Clou...
Artjoker Software Development Company
 
SparkLabs Primer on Artificial Intelligence 2025
SparkLabs Group
 
MASTERDECK GRAPHSUMMIT SYDNEY (Public).pdf
Neo4j
 
AI and Robotics for Human Well-being.pptx
JAYMIN SUTHAR
 
Tea4chat - another LLM Project by Kerem Atam
a0m0rajab1
 
Accelerating Oracle Database 23ai Troubleshooting with Oracle AHF Fleet Insig...
Sandesh Rao
 
A Strategic Analysis of the MVNO Wave in Emerging Markets.pdf
IPLOOK Networks
 
Economic Impact of Data Centres to the Malaysian Economy
flintglobalapac
 
Software Development Methodologies in 2025
KodekX
 
AI Unleashed - Shaping the Future -Starting Today - AIOUG Yatra 2025 - For Co...
Sandesh Rao
 
New ThousandEyes Product Innovations: Cisco Live June 2025
ThousandEyes
 
REPORT: Heating appliances market in Poland 2024
SPIUG
 
Google I/O Extended 2025 Baku - all ppts
HusseinMalikMammadli
 
cloud computing vai.pptx for the project
vaibhavdobariyal79
 
The-Ethical-Hackers-Imperative-Safeguarding-the-Digital-Frontier.pptx
sujalchauhan1305
 
Get More from Fiori Automation - What’s New, What Works, and What’s Next.pdf
Precisely
 

Brk 135 t-ccna_switching

  • 1. © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public BRK-135T CCNA Switching 1 CCNA Switching Snezhy Neshkova, CCIE # 11931 Technical Manager US Academy Conference 2008
  • 2. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 2 Agenda ƒ High Availability Campus Design Overview ƒ STP Operations ƒ STP Variances ƒ Rapid PVST+ Configuration ƒ Troubleshooting Spanning Tree Protocol
  • 3. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 3 Spanning Tree Protocol
  • 4. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 4 High Availability Campus Design ƒ Modularity, structure, and hierarchy ƒ Network redundancy and network protocols Link redundancy (trunks, channels and fiber) Redundancy in the distribution block Redundancy and routing design ƒ Resilient campusnetwork designSiSiSiSi Intranet Internet
  • 5. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 5 Data Center WAN Internet Si Si Si Si Si Si Si Si Si Si Si Si Si Si Access Core Distribution Distribution Access High Availability Campus Design Structure, Modularity, and Hierarchy
  • 6. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 6 Hierarchical Campus Network Server Farm WAN Internet PSTN Si Si Si Si Si Si Si Si Si Si Si Si Not This !! Structure, Modularity and Hierarchy
  • 7. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 7 SiSiSiSiSiSiSiSiSiSiSiSi Hierarchical Network Design Building Block Access Distribution Core Distribution Access• Offers hierarchy—each layer has specific role • Modular topology—building blocks • Easy to grow, understand, and troubleshoot • Creates small fault domains— Clear demarcations and isolation • Promotes load balancing and redundancy • Promotes deterministic traffic patterns • Incorporates balance of both Layer 2 and Layer 3 technology, leveraging the strength of both• Utilizes Layer 3 Routing for load balancing, fast convergence, scalability, and control Without a Rock Solid Foundation the Rest Doesn’t Matter
  • 8. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 8 Access Layer Feature Rich Environment ƒ It’s not just about connectivity ƒ Layer 2/Layer 3 feature rich environment; convergence, HA, security, QoS, IP multicast, etc. ƒ Intelligent network services: QoS, trust boundary, broadcast suppression, IGMP snooping ƒ Intelligent network services: PVST+, Rapid PVST+, EIGRP, OSPF, DTP, PAgP/LACP, UDLD, FlexLink, etc ƒ Cisco Catalyst integrated security features IBNS (802.1x), (CISF): port security, DHCP snooping, DAI, IPSG, etc. ƒ Automatic phone discovery, conditional trust boundary, power over Ethernet, auxiliary VLAN, etc. ƒ Spanning tree toolkit: Portfast, UplinkFast, BackboneFast, LoopGuard, BPDUGuard, BPDUFilter, RootGuard, etc. Access Distribution CoreSiSiSiSiSiSiSiSi
  • 9. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 9 SiSiSiSi Distribution Layer Policy, Convergence, QoS, and High Availability ƒ Availability, load balancing, QoS and provisioning are the important considerations at this layer ƒ Aggregates wiring closets (access layer) and uplinks to core ƒ Protects core from high density peering and problems in access layer ƒ Route summarization, fast convergence, redundant pathload sharing ƒ HSRP or GLBP to provide first hop redundancySiSiSiSi Access Distribution Core
  • 10. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 10 SiSiSiSi Core Layer Scalability, High Availability, and Fast Convergence ƒ Backbone for thenetwork -connects network building blocks ƒ Performance and stability vs. complexity -less is more in the core ƒ Aggregation point for distribution layer ƒ Separate core layer helpsin scalability duringfuture growth ƒ Keep the design technology- independentSiSiSiSi Access Distribution Core
  • 11. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 11 Foundation Services ƒ Layer 3 routing protocols ƒ Layer 2 redundancy—spanning tree PVST+ - STP (802.1D-1998) Rapid PVST+ - RSTP (802.D-2004) ƒ Trunking protocols—(isl/.1q) ƒ Unidirectional link detection ƒ Load balancing Etherchannel link aggregation CEF equal cost load balancing ƒ First hop redundancy protocols VRRP, HSRP, and GLBP Spanning Tree Routing HSRP GLBP Trunking LoadBalancing
  • 12. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 12 Best Practices— Spanning Configuration ƒ Onlywhen you have to! ƒ More common in thedata center ƒ Required when a VLAN spans access layer switches ƒ Required to protect against ‘user side’loops ƒ Use Rapid PVST+ for best convergence ƒ Take advantage of the Spanning Tree Toolkit Data Center WAN Internet Layer 3 Equal Cost Links Layer 3 Equal Cost Links Layer2 Loops Same VLAN Same VLAN Same VLAN Si Si Si Si Si Si Si Si Si Si Si Si Si Si
  • 13. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 13 Multilayer Network Design ƒ Each access switch hasunique VLANs ƒ No layer 2 loops ƒ Layer 3 link between distribution ƒ No blocked links ƒ At least some VLANs span multiple access switches ƒ Layer 2 loops ƒ Layer 2 and 3 running over link between distribution ƒ Blocked linksSiSiSiSiSiSiSiSi Vlan 10 Vlan 20 Vlan 30 Vlan 30 Vlan 30 Vlan 30 Layer 2 Access with Layer 3 Distribution
  • 14. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 14 Routing to the Edge Layer 3 Distribution with Layer 3 Access ƒ Move the Layer 2/3 demarcation to the network edge ƒ Upstream convergence times triggered by hardware detection of light lost from upstream neighbor ƒ Beneficial for the right environment 10.1.20.0 10.1.120.0 VLAN 20 Data VLAN 120 Voice VLAN 40 Data VLAN 140 Voice 10.1.40.0 10.1.140.0 EIGRP/OSPF EIGRP/OSPF GLBP ModelSiSiSiSi Layer 3 Layer 2 Layer 3 Layer 2 EIGRP/OSPF EIGRP/OSPF
  • 15. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 15 STP Operations STP Convergence Steps Step 1: Elect a Root Bridge The switch with the lowest Bridge ID wins; the standard Bridge ID is 2-byte priority followed by a MAC address unique for the switch Step 2: Elect the Root Ports The one port on the each switch with the least cost path back to the root Step 3: Elect the Designated and Non-Designated Ports When multiple switches connect to the same segment; this is the switch that forwards the least cost Hello onto the segment Three step process STP uses to create a loop-free topology
  • 16. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 16 STP Operations STP Port States and BPDU Timers in the Operation of STP Port States Processes Blocking Listening Learning Forwarding Disable Receives and process BPDUs 9 9 9 9 8 Forward data frames received on interface 8 8 8 9 8 Forward data frames switched from another interface 8 8 8 9 8 Learn MAC address 8 8 9 9 8 1Return to blocking if not lowest cost path to root bridge BPDU Timers Hello Time ƒ The hello time is the time between each BPDU frame that is sent on a port ƒ This is equal to 2 seconds by default, but can be tuned to be between 1 and 10 seconds Forward Delay ƒ The forward delay is the time spent in the listening and learning state ƒ This is by default equal to 15 seconds for each state, but can be tuned to be between 4 and 30 seconds Maximum Age ƒ The max age timer controls the maximum length of time a switch port saves configuration BPDU information ƒ This is 20 seconds by default, but can be tuned to be between 6 and 40 seconds
  • 17. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 17 A Root C Peer D Peer 1 2 2 1 2 2 1 RP DP DP RP DP DP RP NDP 1 Core Distribution B Peer 32768:000000000002 8192:000000000001 32768:000000000004 32768:000000000003 Root Ports: Port with Least Cost Path to the Root Bridge Nondesignated Ports: Ports in Blocking Designated Ports: Ports Selected for Forwarding Direction of BPDU Flow Layer 2 Spanning Tree
  • 18. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 18 Layer 2 Hardening ƒ Place the Root where you want it Root Primary/Secondary Macro HSRP/GLBP ƒ The root bridge should stay where you put it Rootguard Loopguard UplinkFast UDLD ƒ Only end station traffic should be seen on an edge port BPDU Guard Root Guard PortFast Port-securitySiSiSiSi BPDU Guard or Rootguard PortFast Rootguard UplinkFast STP Root Spanning Tree Should Behave the Way You Expect Loopguard Loopguard Port-Security
  • 19. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 19 *Also Supported with MST and Rapid PVST+ Spanning Tree Features ƒ PortFast*:Bypass listening-learning phase for access port ƒ UplinkFast:Three to five seconds convergence after link failure ƒ BackboneFast:Cuts convergence time by Max_Age for indirect failure ƒ LoopGuard*:Prevents alternate or root port from becoming designated in absence of BPDUs ƒ RootGuard*:Prevents external switches from becoming root ƒ BPDUGuard*:Disable PortFast enabled port if a BPDU is received ƒ BPDUFilter*:Do not send or receive BPDUs on PortFast-enabled ports Wiring Closet Switch Distribution Switches Root F F F F F X BSiSiSiSi
  • 20. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 20 What Is Root Guard? SiSiSiSiSiSiSiSi Root GLBP Active RP DP BP ƒ Root guard forces a Layer2 LAN interface to be a designated port ƒ If spanning-tree calculations cause a port to be selected as the root port, the port transitions to the root- inconsistent(blocked) state to prevent the customer's switch from becoming the root switch or being in the path to the root. SW(config)# interface fa0/3 SWconfig-if)# spanning-tree rootguard
  • 21. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 21 UplinkFast ƒ Spanning Tree enhancement to reduce failover convergence time ƒ Used when recovery path is known and predictable ƒ Enabled on access switch ƒ Bypasses ‘listening’and ‘learning’stages of STP ƒ Reduces failover time to 2–3 seconds from 30 seconds ƒ Auto-populates upstream address tables (dummy mcast) 2 F F F B 1 Root F F 1SiSiSiSi Switch(config)# spanning-tree uplinkfast
  • 22. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 22 BackboneFast ƒ Spanning Tree enhancement to reduce failover convergence time ƒ Targeted at indirectfailures ƒ Enabled on all switches ƒ Bypasses ‘max-age’ ƒ Reduces failover time to 30 seconds from 50 seconds 3 F F F F SiSiSiSi F B Root Switch(config)# spanning-tree backbonefast
  • 23. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 23 PortFastSiSiSiSiSiSiSiSi Root RP DP ƒUsed on Access Ports (Edge Port) that are NOT connected to other switches or hubs ƒOptimizes the convergence by simply ignoring the Listening and Learning states of the port ƒImmediately puts the port into Forwarding state when the port is physically working BP Switch(config-if)# spanning-tree portfast
  • 24. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 24 What Is BPDU Guard? SiSiSiSiSiSiSiSi Root ƒ PortFast BPDU guard can prevent loops by moving PortFast-configured interfaces that receive BPDUs to errdisable,rather than running Spanning Tree across that port ƒ This keeps ports configured with PortFast from being incorrectly connected to another switch Switch(config)# spanning-tree portfast bpduguard or Switch(config-if)# spanning-tree bpduguard enable 1w2d: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port FastEthernet3/1 with BPDU Guard enabled. Disabling port. 1w2d: %PM-4-ERR_DISABLE: bpduguard error detected on Fa3/1, putting Fa3/1 in err-disable state
  • 25. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 25 Link Redundancy—UDLD Aggressive Mode UDLD ƒ Default UDLD timers (15 second hellos) are intended to take down link prior to 802.1d spanning tree listening/learning transition ƒ Aggressive mode—after aging on a previously bi-directional link—tries eight times (once per second) to reestablish connection then err- disables port ƒ Aggressive mode protects against One side of a link has a port stuck (both Tx and Rx) One side of a link remains up while the other side of the link has gone down ! Global configuration udld aggressive udld message time 7 ! Interface interface GigabitEthernet8/1 udld port aggressiveSiSiSiSi Tx Tx Rx Rx
  • 26. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 26 Spanning Tree Verification 3550# show spanning-tree summary Switch is in pvst mode Root bridge for: VLAN0001 EtherChannel misconfig guard is enabled Extended system ID is enabled Portfast is disabled by default PortFast BPDU Guard is disabled by default Portfast BPDU Filter is disabled by default Loopguard is disabled by default UplinkFast is disabled BackboneFast is disabled Pathcost method used is short Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 0 0 0 2 2 VLAN0005 0 0 0 2 2 ---------------------- -------- --------- -------- ---------- ---------- 2 vlans 0 0 0 4 4 3550# show spanning-tree VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 24577 Address 0005.ddc5.8300 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 24577 (priority 24576 sys-id-ext 1) Address 0005.ddc5.8300 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 15 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- ------------------------ Gi0/12 Desg FWD 19 128.12 P2p Po1 Desg FWD 3 128.65 P2p (etc, for additional vlans)
  • 27. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 27 Spanning Tree Best Practice “How Can I Have a Spanning Tree Loop? I Don’t Have Spanning Tree Enabled?” Cisco Recommends Leaving STP-Enabled for the Following Reasons: ƒ If there is a loop (induced by mispatching, bad cable, and so on), STP will prevent detrimental effects to the network caused by multicast and broadcast data ƒ Protection against an EtherChannelbreaking down ƒ Most networks are configured with STP, giving it maximum field exposure; more exposure generally equates to stable code ƒ Protection against dual attached NICs misbehaving (or bridging enabled on servers) ƒ The software for many protocols (such as PAgP, IGMP snooping, and trunking) is closely related to STP; running without STP may lead to undesirable results
  • 28. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 28 Spanning Tree Standards and Features Spanning Tree Toolkit, 802.1D, 802.1s, 802.1w ƒ 802.1D/1998:Legacy standard for bridging and Spanning Tree (STP) ƒ 802.1D/2004:Updated bridging and STP standard; includes 802.1s, 802.1t, and 802.1w ƒ 802.1s:Multiple Spanning Tree Protocol (MSTP)—maps multiple VLANs into the same Spanning Tree instance ƒ 802.1t:MAC address reduction/extended system ID—moves some BPDU bits to high-numbered VLANs from the priority field, which constrains the possible values for bridge priority; unique “MAC”per chassis not port ƒ 802.1w:Rapid Spanning Tree Protocol (RSTP)—improved convergence over 1998 STP by adding roles to ports and enhancing BPDU exchanges ƒ Cisco Features:Per VLAN Spanning Tree (PVST), PVST+, UpLinkFast, BackboneFast, BPDU Guard, RootGuard, LoopGuard, UDLD A B STOP
  • 29. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 29 STP Variance DEC STP pre-IEEE 802.1t—802.1d maintenance IEEE 802.1w—Rapid STP (RSTP) 802.1D—Classic STP 802.1s—Multiple STP (MST)
  • 30. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 30 Cisco Spanning-Tree toolkit PortFast Lets the access port bypass the listening and learning phases Root Guard Prevents external switches from becoming the root STP enhancements to 802.1(d,s,w) BackboneFast Cuts convergence time by MaxAge for indirect failure UplinkFast Provides 3-to-5 second convergence after link failure Loop Guard Prevents the alternate or root port from being elected unless Bridge Protocol Data Units (BPDUs) are present BPDU Guard Disables a PortFast-enabled port if a BPDU is received BPDU Filter Prevents sending/receiving BPDUs on PortFast-enabled ports
  • 31. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 31 STP Variance Per-VLAN Spanning Tree Plus (PVST+) Provides a separate 802.1D spanning tree instance for each VLAN configured in the network. This includes PortFast, UplinkFast, BackboneFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard. MST Provides up to 16 instances of RSTP (802.1w) and combines many VLANS with the same physical and logical topology into a common RSTP instance. This includes, PortFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard. Cisco Proprietary Rapid PVST+ Provides an instance of RSTP (802.1w) per VLAN. This includes PortFast, BPDU Guard, BPDU Filter, Root Guard, and Loop Guard.
  • 32. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 32 05101520253035PVST+Rapid PVST+ UpstreamDownstream Optimizing L2 Convergence ƒ Rapid-PVST+ greatly improves the restoration times for any VLAN that requires a topology convergence due to link UP ƒ Rapid-PVST+ also greatly improves convergence time over Backbone fast for any indirect link failures ƒ PVST+ (802.1d) Traditional Spanning Tree Implementation ƒ Rapid PVST+ (802.1w) Scales to large size (~10,000 logical ports) Easy to implement, proven, scales ƒ MST (802.1s) Permits very large scale STP implementations (~30,000 logical ports) Not as flexible as Rapid PVST+ Time to Restore Data Flows (sec) PVST+, Rapid PVST+ or MST
  • 33. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 33 RAPID SPANNING TREE 802.1w
  • 34. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 34 RSTP: New Concepts ƒ New Port Roles and States ƒ Modified BPDU ƒ Proposal/Agreement messages between bridges ƒ BPDU handling ƒ New topology change mechanism ƒ PVST+/802.1D Compatibility
  • 35. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 35 Rapid PVST+ ƒ Rapid PVST+ is the IEEE 802.1w (RSTP) standard implemented per VLAN. ƒ Each Rapid PVST+ instance on a VLAN has a single root switch. You can enable and disable STP on a per- VLAN basis when you are running Rapid PVST+. ƒ Rapid PVST+ uses point-to-point wiring to provide rapid convergence of the spanning tree. ƒ The spanning tree reconfiguration can occur in less than 1 second with Rapid PVST+ (in contrast to 50 seconds with the default settings in the 802.1D STP).
  • 36. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 36 Rapid PVST+ defines 4 port roles: ƒ Root port -If Rapid PVST+ selects a new root port, it blocks the old root port and immediately transitions the new root port to the forwarding state. ƒ Designated port ƒ Alternate port ƒ Backup port Port state (blocking, forwarding, learning) is independent from the role Rapid PVST+ roles (1) Both blocking
  • 37. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 37 Rapid PVST+ roles (2) Root A B R R Root Port R Root Port: Port receiving the best BPDU for the bridge – shortest path to the Root in terms of path cost
  • 38. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 38 Rapid PVST+ roles (3) Root A B R D D D R Root Port R Designated Port D Designated Port: Port sending the best BPDU on a segment
  • 39. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 39 Rapid PVST+ roles (4) Root A B R D D D R Root Port R Designated Port D Alternate Port Alternate Port: Port blocked by BPDUs from a different bridge – redundant path to the Root
  • 40. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 40 Rapid PVST+ roles (5) Root A B R D D D R Root Port R Designated Port D Backup Port Alternate Port Backup Port: Port blocked by BPDUs sent from the same bridge – redundant path to a segment
  • 41. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 41 Modified BPDU ƒ Protocol version now 2 (was 0) ƒ No more distinct TCN BPDU ƒ Flag field changes • 802.1D bridges drop RSTP BPDUs
  • 42. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 42 Modified BPDU (2) ƒ BPDUs now act as keepalives: – All bridges send BPDUs every hello time (PVST+ used to relay BPDUs from the root) – Port information invalidated in 3 x hello time max Ù3 BPDUs lost – No more Max Age or Message Age fields – a hop count is used instead inside a region ÖFaster failure detection
  • 43. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 43 Agreement/Proposal ƒ Explicit handshake mechanism between bridges ƒ Upon link up event, bridge sends a proposal to become designated for that segment (designated bridge is the one leading to the root) ƒ Response is an agreementif remote bridge selects the port on which it received the proposal as its root port ƒ As soon as agreement is received, port moves to forwarding
  • 44. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 44 Agreement/Proposal A B C B Root ƒ Ahas a better priority than B ƒ Asends a proposal to Bto become designated ƒ Bcompares the received priority and replies with an agreement –B’s port becomes Root Port • The same process is repeated when a new bridge is inserted Prop Agree
  • 45. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 45 Rapid Transition ƒFor a rapid transition to occur • Make sure you properly identify: » Edge ports (enabled via Portfast) » Point-to-point links (derived from duplex mode by default) ƒIt is very important to check duplex settings between two bridges –else, no Proposal/Agreement mechanism !
  • 46. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 46 Protocol Migration (1) Mix of 802.1D and 802.1w Bridges: ƒ 1D bridges drop 1w BPDUs Ö1D Bridges always end up sending BPDUs • After Migration Delay (3s), RSTP bridge starts sending 802.1D BPDU if it detects a legacy bridge (on a per-port basis). A (1w) B (1w) C (1D) RSTP BPDU STP BPDU
  • 47. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 47 Protocol Migration(2) • Cannot detect if 802.1D bridge is removed if it is not designated (otherwise it would send BPDUs). • If C goes away, force protocol migration manually (set spantree mst x/y redetect- neighbor) • 1D-1w interoperability = slow convergence: Ötry to avoid it. A (1w) B (1w) C (1D) STP BPDU
  • 48. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 48 Configuring Rapid-PVST+ ƒ RSTP fast convergence on a per-VLAN basis ƒ Each VLAN runs its own RSTP instance and sends its own RSTP BPDU, just like PVST+ CiscoIOS# configure terminal CiscoIOS(config)# spanning-tree mode rapid-pvst+
  • 49. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 49 Configuring Rapid-PVST+ in Distribution Dist-2 Dist-1 FWD: VLANs 6-10 BLK: VLANs 1-5 Trunk FWD: VLANs 1-5 BLK: VLANs 6-10 FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 1-5 Sec. Root: VLANs 6-10 Root: VLANs 6-10 Sec. Root: VLANs 1-5 FWD: VLANs 6-10 BLK: VLANs 1-5 Cisco IOS spanning-tree extend system-id spanning-tree mode rapid-pvst+ ! Set spanning tree mode to rapid-pvst+ spanning-tree vlan 1-5 root primary spanning-tree vlan 6-10 root secondary
  • 50. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 50 Configuring Rapid-PVST+ in Access Trunk FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 1-5 Sec. Root: VLANs 6-10 FWD: VLANs 6-10 BLK: VLANs 1-5 FWD: VLANs 1-5 BLK: VLANs 6-10 Root: VLANs 6-10 Sec. Root: VLANs 1-5 FWD: VLANs 6-10 BLK: VLANs 1-5 Acc-1 Acc-1 CiscoIOS spanning-tree extend system-id ! Enable MAC address reduction. This is not a requirement spanning-tree mode rapid-pvst+ ! Set spanning tree mode to rapid-pvst+
  • 51. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 51 Spanning Tree Protocol Troubleshooting Methodology ƒ Start now—be proactive ƒ Divide and conquer ƒ Document Spanning Tree topology ƒ Implement Spanning Tree enhancement features ƒ Develop recovery plan to include data collection for root cause analysis Data Center WAN Internet Layer 3 Equal Cost Links Layer 3 Equal Cost Links Layer2 Loops Si Si Si Si Si Si Si Si Si Si Si Si Si Si
  • 52. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 52 Spanning Tree Protocol Documenting Spanning Tree Topology Corporate Network 3/1–4 3/1–4 1/1 1/1 Gig 0/1 155.3.77.254 Gig 0/1 155.3.76.254 VLAN186 VLAN187 Root: 1,3,5,7,9,187 0001.c912.7800 Root: 2,4,6,8,186 0003.6b73.9700 F: 1,2,3,4,5,6,7,8,9 B: 4 F: 1,2,3,4,5,6,7,8,9 4/1 4/1 4/2 4/2 4/3 4/3 4/4 4/4 1/1 1/2 1/1 1/2 1/1 1/2 1/1 1/2 0001.c967.7800 DIST-01 192.168.1.1 DIST-02 192.168.1.2 Closet1 192.168.1.11 Closet2 192.168.1.12 Closet3 192.168.1.13 Closet4 192.168.1.14 0001.c9dd.7800 0001.c932.9700 0001.c949.9700 F: 1,2,3 F: 1,4,5 F: 1,6,7 F: 1,8,9 B: 1,3 B: 2 F: 1,2,3 F: 1,4,5 F: 1,6,7 F: 1,8,9 B: 1,5 B: 1,7 B: 6 B: 1,9 B: 8
  • 53. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 53 Spanning Tree Protocol STP Loop Recovery ƒ Do not power off switches—pull/shut redundant links ƒ If possible, initially disable ports that should be blocking ƒ Check and physically remove the connections to the ports that should be blocking ƒ Set up remote access to your network and call the TAC
  • 54. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 54 IOS#show spanning-tree vlan 1 brief VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 1 Address 0060.8355.7b00 Cost 23 Port 1 (GigabitEthernet1/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 0007.0e8f.0880 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Interface Designated Name Port ID Prio Cost Sts Cost Bridge ID Port ID -------------------------- ----------- ------ ------- ------- GigabitEthernet1/1 128.1 128 4 FWD 67 32768 0005.5f33.dc01 128.1 FastEthernet3/48 128.176 128 19 FWD 48 32768 0030.7bdd.5080 128.16 Spanning Tree Protocol Troubleshooting Commands
  • 55. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 55 IOS#show spanning-tree vlan 1 VLAN0001 Spanning tree enabled protocol rstp Root ID Priority 32768 Address 0030.7b4e.4801 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32768 Address 0030.7b4e.4801 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- ------------------------ Fa2/1 Desg FWD 19 128.129 P2p Peer(STP) Spanning Tree Protocol Troubleshooting Commands
  • 56. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 56 IOS#show spanning-tree summary Root bridge for: VLAN0010. Extended system ID is enabled PortFast BPDU Guard is enabled EtherChannel misconfiguration guard is disabled UplinkFast is disabled BackboneFast is enabled Default pathcost method used is short Name Blocking Listening Learning Forwarding STP Active ------------------------------------- ------------- ------------- ---------------- -------- VLAN0001 0 0 0 2 2 VLAN0010 0 0 0 1 1 VLAN1002 0 0 0 1 1 VLAN1003 0 0 0 1 1 VLAN1004 0 0 0 1 1 VLAN1005 0 0 0 1 1 ------------------------ ------------- ------------- ------------- ---------------- 6 VLANs 0 00 7 7 Spanning Tree Protocol Troubleshooting Commands Root for Listed VLANs
  • 57. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 57 IOS# show proc cpu CPU utilization for five seconds: 1%/0%; one minute: 2%; five minutes: 2% PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process 1 0 1 0 0.00% 0.00% 0.00% 0 Chunk Manager <…some output removed…> 79 0 256 0 0.00% 0.00% 0.00% 0 mls-msc Process 80 30508 461976 66 0.40% 0.43% 0.44% 0 Spanning Tree 81 108 27024 3 0.00% 0.00% 0.00% 0 Ethchnl <…some output removed…> 162 12 41 292 0.00% 0.01% 0.00% 1 Virtual Exec IOS# show spanning-tree summary <…some output removed…> Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 1 0 0 1 2 <…some output removed…> VLAN1005 0 0 0 1 1 ---------------------- -------- --------- -------- ---------- ---------- 282 vlans 1 0 0 282 283 Spanning Tree Protocol Troubleshooting Commands Number of Spanning Tree Instances
  • 58. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 58 IOS#show spanning-tree vlan 1 detail VLAN0001 is executing the ieee compatible Spanning Tree protocol Bridge Identifier has priority 32768, address 0005.7495.9101 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32768, address 0001.c912.7800 Root port is 70 (GigabitEthernet2/6), cost of root path is 4 Topology change flag not set, detected flag not set Number of topology changes 4 last change occurred 02:17:20 ago from Port-channel1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 70 (GigabitEthernet2/6) of VLAN0001 is forwarding Port path cost 4, Port priority 128, Port Identifier 128.70. Designated root has priority 32768, address 0001.c912.7800 Designated bridge has priority 32768, address 0001.c912.7800 Designated port id is 128.70, designated path cost 0 Timers: message age 2, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default BPDU: sent 7, received 4162 Port 833 (Port-channel1) of VLAN0001 is blocking Port path cost 4, Port priority 128, Port Identifier 128.833. Designated root has priority 32768, address 0001.c912.7800 Designated bridge has priority 32768, address 0001.c912.7800 Designated port id is 128.769, designated path cost 0 Timers: message age 1, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default BPDU: sent 4, received 134836 Spanning Tree Protocol Troubleshooting Topology Change Don’t Forget PortFast
  • 59. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 59
  • 60. BRK-135T CCNA Switching © 2008 Cisco Systems, Inc. All rights reserved. Cisco Public 60